Recent advances in technology of confocal microscopy have opened new avenues for understanding the biology of cells and their interactions with other cells. For example, now that we can examine living cells, we can study the translocation of proteins in response to stimulation in real time. With the multiphoton lasers, greater depth can be reached so that whole embryos, islets, whole fat pads or other small structures can be examined thoroughly with optical, rather than physical, sectioning. With the new software that is now available with these confocal microscopes, sophisticated analyses, whether of calcium flux, unmixing spectral overlap, FRET or FRAP are facilitated. These cell biological approaches are key to an improved understanding of normal metabolic physiology as well as the pathophysiological processes leading to types 1 and 2 diabetes and associated complications. This application requests funds for a Zeiss Laser Scanning Microscope (LSM) 510 Duo, which will be added to the NIH-funded Diabetes and Endocrinology Research Center at the Joslin Diabetes Center. This instrument will be operated and maintained by the Advanced Microscopy Facility at Joslin. The usage of this instrument is estimated at 75-100%, distributed between at least 18 NIH-funded investigators at Joslin and 2 of our external colleagues. The research projects are relevant to both type 1 and type 2 diabetes and associated complications. These studies address a number of areas of diabetes research including autoimmunity related to type 1 diabetes, stem cells, islet function and regeneration, mechanisms of insulin resistance, type 2 diabetes, obesity, metabolism and vascular complications. PUBLIC HEALTH RELEVANCE: Diabetes has reached epidemic prevalence causing an increasing burden to the health care costs not just of the United States but also the world. The Joslin Diabetes Center, located within the Longwood Medical Area and closely tied to Harvard Medical School, is uniquely focused with a mission to provide health care, research and education on diabetes that will improve the lives of people with diabetes. This state-of-the-art confocal microscope together with the expertise and research of investigators listed in this application should lead to new understanding into cellular metabolism and of the causes and consequences of diabetes and to new advances for the treatment of diabetes